Robots have been deployed across numerous industrial and manufacturing environments to promote reliability and cost savings. For example, a robotic arm can move objects to perform tasks, including assembly, packaging, inspection, etc. A manipulator is typically placed on an extended robotic arm such that the point of manipulation may be easily adjusted. Controlling the manipulator precisely through the extended robotic arm, however, may be challenging. For example, the manipulator typically has a significant mass; to support such a load with a desired precision extending all the way to the root joint of the robot, each joint in the kinematic chain between the arm and root joint has to operate within a very strict tolerance for position errors. In other words, all joints in the kinematic chain have to operate at the same or better precision compared with the desired precision at the target. For example, an angular precision of the motor at the root of the arm is required to be within 0.03 degree to guarantee that a manipulator located at the end of a two-meter robotic arm is within 1 millimeter of the target position. Such strict requirements result in complexity and high cost.
Additionally, the robotic system needs to apply large forces to dampen any possible dynamic effects of the overall arm motion. Even for the straightforward task of handling a lightweight target, delivering the target with sub-millimeter or sub-degree precision may still be challenging. For example, in a simple assembly task, a screw may weigh just a few milligrams at the end of the two-meter robotic arm; yet the robotic machinery for delivering the screw must be able to support itself—including all the motors, gearboxes and electronics—when fully extended while maintaining precise position control at every joint and, additionally, compensate for backlash, bending, slippage and cumulative errors in the kinematic chain. This, again, significantly increases the design complexity and manufacturing cost of the robotic system.
Conventionally, a robotic system that can perform high-precision target manipulations utilizes parts and techniques that are specialized to the given task. This not only requires a specific and careful design, thereby increasing the system complexity and cost, but also limits the general applicability of the robotic system. Consequently, there is a need for a robotic system that provides precise target manipulations without the need for specialized or task-specific components or techniques.